Connecting microsized devices using ablative films

ABSTRACT

A method of providing connectivity to a microsized device, the method includes the steps of providing an ablative base material having at least a top surface; providing a die having a first and second surface and having bonding pads at least upon the first surface; placing the die with the at least first surface of the die contacting the at least first surface of the ablative base material; and ablating a channel in the ablative material proximate to the die.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of and claims priority from U.S. patent applicationSer. No. 11/737,187 filed Apr. 19, 2007, the content of which isincorporated herein by reference.

This application also is related to U.S. patent application Ser. No.______ filed concurrently herewith, titled “Connecting MicrosizedDevices Using Ablative Films”, by M. Zaki Ali, et al., having anattorney docket number of 93538A, and claiming priority to U.S. patentapplication Ser. No. 11/737,187 as a continuation application.

FIELD OF THE INVENTION

The invention relates generally to the field of microsized devices andin particular to processes providing connections to microsized devices,including processes based on the use of ablative films to connect aplurality of microsized devices to one another. More specifically, theinvention relates to ablative means for providing fluidic, electrical,photonic, magnetic, and mechanical connections to microsized devices.

BACKGROUND OF THE INVENTION

Microsized devices include, for example, micro-accelerometers andmicro-gyroscopes for detecting linear and angular accelerations asmanufactured by Analog Devices, Inc., chemically sensitive field effecttransistors, used to detect the presence of certain molecular vaporssuch as carbon monoxide or ethanol, pressure sensors for measurement ofpressures in automotive systems or micro phonic sensors, such as thoseemployed in cell phones to detect and reproduce audio sounds, andoptical sensors for detecting the presence of objects by infra-redradiation. These and other microsized devices are well known topractioners of micro systems technology (MST). Also well known in thatart are the difficulties encountered in inexpensive packaging of suchmicrosized devices, in part because their small sizes require accuratepositioning of connections and also because the connections may be ofmany different types, for example electrical, mechanical, or fluidic(vapor). Because the objects are small, many interconnected devices maybe incorporated for systems applications. Additionally, since thedevices are small, connections must be made so as not to perturb theirfunctionality, for example by mechanical stress, especially in the faceof changes in external environment in which collections of devices areoperated, such as temperature or humidity.

Previous means employed for the connection of microdevices have includedthe use of automated wire bonding apparatus, use of ball grid arraystechnology, fabrication of special packages using materials havingtemperature matched expansion coefficients, and the use of packagesencapsulating devices in inert or chemically controlled atmospheres.Although these techniques offer sophisticated solutions, theirimplementation is not without expense, as is well known, for example, inthe case of the packaging of micromirror devices (MMD) as manufacturedby Texas Instruments, Inc. More recently, lower cost solutions havebecome available for mounting and connecting arrays of microsizeddevices on polymer films, for example those using films on which arepatterned conductive lines, which may be deposited by many techniques,including ink jet printing of fluids. Such fluids may be conductive asdeposited or may become conductive upon subsequent processing, forexample by thermal annealing. These films are typically flexible andtherefore are less likely to perturb the functionality of the microsizeddevices by mechanical stress.

One means of depositing conductive lines, related to the presentinvention, is by depositing conductive fluids to fill channels made inpolymer films, for example channels made by laser ablation of polymerfilms, hereinafter referred to as ablative films. As is well known inthe art of MST, microsized devices may then be placed proximate to theconductive lines; and connections, typically electrical, may be madeusing a variety of techniques, including wire-bonding, flip chipbonding, electroplating, and deposition of conductive materials,including deposition of conductive fluids by inkjet means, typically toensure the reliable connection of electric leads to the devices or“die.”

Referring to FIG. 1 a, there is shown a cross-section of a prior artablative film 5. The ablative film 5 includes a substrate 10, typicallya flexible polymer such as a polyamide or polycarbonate, and one or moreenergy-absorbing layers 20 which can be removed, all or in part, byexposure to intense radiation, or in other words, can be ablated, forexample by radiation from a near IR laser. Ablative film compositionswhich can be removed by radiation from a near IR laser are disclosed,for example, by M. Zaki Ali, et al. in US Patent Publication2005/0227182, which further contemplates using the ablative films, onceablated, as photolithographic masks for subsequent image wiseultraviolet exposure of flexography materials. The ablative filmsdescribed in US 2005/0227182 may contain additional layers which servepurposes other than of a substrate or of energy absorbing layers, forexample release layers used in lamination and surface energy controllayers for repelling liquids, so that the ablative films, once ablated,may serve a variety of purposes. Many other material types of polymericablative films and laser ablation processes are well known in the art oflaser ablation and laser processing for the manufacture of patterns andstructures. For example, U.S. Pat. No. 7,115,514 by Richard Stoltz andassigned to Raydiance, Inc., describes a laser ablation process usingshort pulses at wavelengths shorter than the near IR are described forablating a wide variety of materials including metals and inorganicmaterials and for altering their surfaces by ablation.

Referring to FIG. 1 b, there is shown a cross-section of another priorart ablative film 5 of a more complex structure. The ablative film 5includes a substrate 10, and multiple layers 30, some of which areenergy absorbing layers. These layers can be removed, all or in part, byexposure to intense radiation. Other layers may provide desired colorsor surface properties, such as hydrophobicity, or may comprise releaselayers to allow separation of the layers, and may be removed (ablated)when nearby underlying or overlying energy absorbing layers absorbradiation.

Referring to FIGS. 2 a-2 b, there is illustrated in cross-section andtop-view, respectively, prior art formation of a channel 40 in anablative film 5 of FIG. 1 a. The ablative film 5 includes the twoenergy-absorbing layers 20 and the substrate 10 as described above. Thebase 50 of the channel 40 may be altered by the ablation process, forexample its surface may be rendered hydrophilic.

Among the many known uses for ablative films, subsequent to patterningby ablation, are those relying on the geometry and surface properties ofthe ablated film to confine deposited fluids, such as fluids containingconductive materials such as metallic particulates. These fluids aretypically deposited by well-known techniques such as ink-jetting orimmersion in fluid baths followed by removal, for example by mechanicalwiping blades, of excess fluid not in the ablative channels. Referringto FIG. 2 c, there is illustrated in cross-section a prior art processfor forming an electrically conductive material 60 in an ablated channel40 in the ablative film 5. For example, the conductor 60 may be formedby jetting (preferably by inkjet printing means) a liquid containing ametallic precursor into the channel 40 and then annealing the liquid toform the conductor 60. The conductor 60, as commercialized, for exampleby Dimatix, Inc. and Cabot Corporation.

The deposition of conductors in channels formed in polymeric films hasfurther been employed to connect together microsized deviceselectrically, for example by positioning microsized devices on the topsurface of polymer films having conductors patterned in channels or onthe film surface, the positioning means being one of mechanicalplacement or, alternatively self assembly, as practiced by AlienTechnologies, Inc. The microsized devices are positioned in anapproximate way near the conductors and then one or more conductivemetal strips are deposited which extend from the microsized device(s) tothe conductor(s) to establish electrical connections. Methods ofself-aligned positioning include alignment by matching geometricalfeatures built into both the microsized devices and the substrate or theuse of chemical constituents deposited pattern wise on the substratewhich attract matching chemical constituents applied to the microsizeddevices as referenced in Sharma, et al., US Patent Publication2006/0134799 and Sharma, et al., US Patent Publication 2006/0057293. Forexample, optically emitting diodes arrays may be so formed for displayapplications.

Although such prior art techniques can provide useable arrays ofinterconnected devices, the process of placement of the microsizeddevices must be sufficiently accurate to allow for the cost effectiveprovision of connections, for example connections made of conductivemetal strips to establish electrical connections. Such accuracy isgenerally difficult to achieve for self-aligned processes and expensiveto achieve by precision pick and place technologies. Moreover, thedeposition of conductive strips is expensive; time consuming andproblematic as to reliability if the connection is to be robust onflexible substrates. Additionally, such techniques are not generallyapplicable to connection types other than electrical, for exampleconnections of the fluidic, magnetic, optical, or mechanical types orconnections of mixed types.

SUMMARY OF THE INVENTION

The present invention is directed to overcoming one or more of theproblems set forth above. Briefly summarized, according to one aspect ofthe present invention, the invention resides in a method of providingconnectivity to a microsized device, the method comprising the steps ofproviding an ablative base material having at least a top surface;providing a die having a first and second surface and having bondingpads at least upon the first surface; placing the die with the at leastfirst surface of the die contacting the at least top surface of theablative base material; and ablating a channel in the ablative materialproximate to the die.

ADVANTAGEOUS EFFECT OF THE INVENTION

The present invention has the following advantage of expanding use ofablative material to include having microsized devices thereon.

The placement of microsized devices may precede the patterning of theprimary routes for connections to or between the devices, includingmechanical, optical, magnetic, fluidic, or electrical.

The connections may be combinations of the types above, achieved withoutsubstantial process complexity over the individual connection types.

The alignment of the microsized devices to the connections may be of aself-aligned nature without the complexity heretofore required ofself-aligned connections to microsized devices.

Records of the position and alignment of microsized devices are includedin the manufacturing process.

These and other aspects, objects, features and advantages of the presentinvention will be more clearly understood and appreciated from a reviewof the following detailed description of the preferred embodiments andappended claims, and by reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a cross-section of a prior art ablative film;

FIG. 1 b is a cross-section of a prior art ablative film;

FIGS. 2 a-2 b illustrate in cross-section and top-view, respectively,prior art formation of a channel in an ablative film;

FIG. 2 c illustrates in cross-section a prior art process for forming anelectrically conductive material in an ablated channel in an ablativefilm;

FIG. 2 d illustrates schematically in cross-section an embodiment ofablative film 70 of the present invention;

FIG. 3 a-b shows top and cross-sectional views of the microsized deviceof the present invention having two contact regions;

FIG. 3 c shows a top view of a microsized device having three contactregions;

FIG. 3 d is an alternative embodiment of FIGS. 3 a-b showing a top viewof a microsized device of the present invention having two contacts;

FIG. 3 e shows a cross-section of a microsized device (die) having acontact region (solid fill) partially extending from the top of the dieover its left edge;

FIG. 4 a shows a view of a microsized device (die) having three contactregions (dotted lines) placed with its top-side down on the top surfaceof an ablative film;

FIG. 4 b shows a view of two microsized devices (die) having contactregions (dotted lines) placed top-side down on the top surface of anablative film;

FIG. 4 c shows the two die of FIG. 4 b including channels formed bylaser ablation of the ablative film extending to the contact regions;

FIGS. 4 d-4 e illustrate a process for forming the channels of FIG. 4 cin a self-aligned manner to the die;

FIGS. 5 a-5 b illustrate deposition by inkjet printing means and bydropper or dipping means of a fluid, for example a conductive ink, intothe ablated channels of FIG. 4 c, as is well known in the arts of inkjetprinting and of fluid coating;

FIG. 6 a illustrates one technique for removal of excess fluiddeposition by dropper means of a fluid using a flexible blade;

FIG. 6 b shows a cross-sectional view of a die, channel, and depositedfluid as in FIG. 2 d but in more detail;

FIG. 7 a-7 c shows a cross-sectional view of a die, channel, anddeposited fluid as in FIG. 2 d but in more detail for the case in whichthe connection to the die is a photonic connection;

FIG. 8 a-8 c shows a cross-sectional view of a die, channel, anddeposited fluid as in FIG. 2 d but in more detail for the case in whichthe connection to the die is a magnetic connection;

FIG. 9 a-9 c shows a cross-sectional view of a die, channel, anddeposited overlayer for the case in which the connection to the die is afluidic connection;

FIG. 10 a-10 f shows a cross-sectional view of a die, channel, anddeposited overlayer for another exemplary case in which the connectionto the die is a fluidic connection;

FIG. 11 a-11 c shows a cross-sectional view of a die, channel, andchannel material for another exemplary case in which the connection tothe die is a mechanical connection;

FIG. 12 a-12 b shows a top and cross-sectional view of a die, channel,and channel material for the case in which the connection to the die isremote, that is the material in the channel is close to the contactregion of the die but not in physical contact; and

FIG. 13 illustrates by top view multiple connections of multiple types,including connections of the electrical, photonic, magnetic, mechanical,and fluidic types, to multiple types of microsized devices, includingdevices that generate and respond to electrical, photonic, magnetic,mechanical, and fluidic signals.

DETAILED DESCRIPTION OF THE INVENTION

Microsized means devices whose features critical to functionality aretypically 1 to 100 microns in linear dimension and which are made inprocesses involving photolithographic exposure of layers of materials tobe patterned by subsequent processing. A micro-fluidic device means amicrosized device whose principal functionality is the transport,analysis, and dispensation of fluid materials (gases and liquids) orinformation concerning the nature of the analyzed fluidic materials,such as, but not limited to sensors of chemical or biological materialsand their physical and chemical properties. Micro-fluidic microdevicesmay also receive information in analog or digital form includingelectrical or optical information and produce fluidic signals such aspressure changes or changes in chemical composition in fluid connectionsin analog or digital form as output. A microsized photonic devicereceives, processes, and/or transmit information in the form of opticaldata, including trains of optical pulses, or analog input or output oflight including wavelength optical signals and may respond to opticalstimulation in a variety of ways, including electrical and mechanicaloutput. Optical microdevices may also receive information in analog ordigital form including electrical or mechanical information and produceoptical signals in analog or digital form as output. Mechanicalmicrosized devices are sensitive to and can produce mechanical stimuliin analog or digital form including quasi-static mechanical motion aswell as acoustic waves and pulses and may a respond to mechanicalstimulation in a variety of ways, including electrical and opticaloutput. Mechanical microdevices may also receive information in analogor digital form including electrical and optical information and producemechanical or acoustical signals in analog or digital form as output.Magnetic microdevices sense magnetic stimuli in analog or digital formincluding quasi-static magnetic fields as well as time varying fieldsand may respond to magnetic stimulation in a variety of ways, includingproducing electrical and optical output. Magnetic microdevices may alsoreceive information in analog or digital form including electrical andoptical information and produce magnetic signals in analog or digitalform as output.

Referring to FIG. 2 d, there is shown one embodiment of ablative film 70of the present invention. The ablative film 70 includes a substrate 80and two energy-absorbing layers 75 in which a microsized device (die) 90has been positioned on the top surface of the ablative film 70 and aself-aligned channel 100 is formed in proximity to one edge of the die90 by laser ablation. As is well known in the art of laser ablation,energy absorbed in one or more energy absorbing layers 75 results in theremoval of material from the energy-absorbing layer and, depending onthe chemical nature of the surrounding layers, removal of material fromadjacent layers. The die 90 in FIG. 2 d is provided with one or morecontact regions comprising metallic bond pads 110 on the side facing theablative film. A liquid 120 containing a metallic precursor has beenjetted, for example by inkjet printing means, into the channel 100. Ametallic precursor is a fluid which, when dried or annealed, is anelectrical conductor, as is well know in the art of printed electronics.The liquid 120 containing a metallic precursor in FIG. 2 d fills thechannel 100 and has flowed under portions of the die 90 adjacent thechannel, thereby providing, when annealed, an electrical and mechanicalconnection to the die 90 by direct contact to the metallic bond pad 110.Advantageously, the electrical connection to the die 90 is madesimultaneously with the process of deposition of the fluid into channel100.

Referring to FIGS. 3 a-3 b, there is shown top and cross-sectional viewsof the microsized device 90 (die). The microsized device 90 includes twocontact regions 130 (disposed symmetrically) partially protected byprotective layers 135 and having a raised support structure 140 betweenand along the sides of the contact regions 130. Provision of the die 90with support structure 140 is advantageous in making various types ofconnections to the die 90, as will be described.

Referring to FIG. 3 c, there is shown a top view of an alternativeembodiment of the microsized device 90 (die) having three contactregions 130 partially protected by protective layers 135 and having araised support structure 140 separating some of the contact regions 130.

Referring to FIG. 3 d, there is shown a top view of an alternativeembodiment of the microsized device 90 (die) having two contact regions130 (disposed non-symmetrically) partially protected by protectivelayers 135 and having a raised support structure 140 separating thecontact regions. The protective layers 135 do not extend to the edge ofthe die 90 in portions of the contact regions 130 in order to provide amore direct path for liquids subsequently deposited near the edge of thedie 90 to flow to the contact regions 130.

Referring to FIG. 3 e, there is shown a cross-sectional view of analternative embodiment of the microsized device 90 (die) having acontact region 130 disposed partially extending from the top of the die90 over its left edge, in order to provide a more direct path forliquids subsequently deposited near the edge of the die 90 to flow tothe contact regions 130. Although FIG. 3 d illustrates electricalconnection to the die 90, the location of protective layer 135 as shownin FIG. 3 d and the use of the raised support structures 140 are usefulin providing all types of contacts to the die 90.

Referring to FIG. 4 a, there is shown a top view of the microsizeddevice 90 (die) having three contact regions 130 placed with itstop-side down on the top surface of an ablative film 70. The die 90 hasbeen lightly affixed to the ablative film 70, for example by pressinginto the film 70 under heat or by depositing a small amount of adhesive(not shown) to portions of the die 90, for example to the raised supportstructure 140 (not visible in this top view as it lies adjacent the topsurface of the substrate) separating some of the contact regions 130.Note the die 90 is not placed with precision; that is, the die centerand the angle of the die 90 with respect to the ablative film 70 are notprecisely controlled.

Referring to FIG. 4 b, there is shown a view of two microsized devices90 (die) having contact regions 130 placed top-side down on the topsurface of an ablative film 70. The die 90 has been lightly affixed tothe ablative film 70, for example by pressing into the film 70 underheat or by depositing a small amount of adhesive to portions of the die90. It is noted the die 90 are not placed with precision; that is, thedie centers and the angles of the die 90 with respect to the ablativefilm 70 and to one another are not precisely controlled.

Referring to FIG. 4 c, there is shown the two die 90 of FIG. 4 b.Channels 150 are preferably formed by laser ablation of the ablativefilm 70 extending to the contact regions 130. The channels 150 areformed in a manner such that the channel direction is aligned with thedirection of the chip, that is, in FIG. 4 c, the channel 150 is formedperpendicular to the edge of the chip nearest the contact region 130,despite the fact that the chip has been oriented at an angle to the edgeof the ablative film 70.

Referring to FIGS. 4 d-4 e, there is shown a process for forming thechannels 150 of FIG. 4 c in a self-aligned manner to the die 90. It isnoted that although FIGS. 4 d-4 e illustrate the embodiment having twoenergy absorbing layers 75 covering the substrate 80, a singleenergy-absorbing layer is also generally adequate. A scanned source ofradiation, for example a laser beam, ablates portions of the ablativefilm 70 until it reaches the edge of the die 90 where its energy isreflected away from the film 70, thereby stopping formation of thechannel 150 precisely at the die edge, regardless of the position andangle of orientation of the die 90. If required, the positions of thenon-precisely placed die 90 are detected with a camera and stored in amemory file. This file is interrogated upon scanning the energy beamsand used to control the scanner to move beams toward the desiredlocations on the die 90 (typically the locations of the contact pads andtypically perpendicular to the edge of the chip nearest the contactregion, despite the fact that the chip may be oriented at an angle tothe edge of the ablative film 70.). It is noted that the die 90 areprincipally supported by the raised support structure 140 separating thecontact regions 130 so that there is some space between the contactregion 130 and the top surface of the ablative film 70.

Referring to FIGS. 5 a-5 b, there is illustrated deposition by inkjetprinting means and by dropper or dipping means of a fluid 160, forexample a conductive ink 160 a (shown later), into the ablated channels150 of FIG. 4 c, as is well known in the arts of inkjet printing and offluid coating. FIG. 5 a illustrates the process of dropping theconductive fluid 160 while it is actually occurring and FIG. 5 billustrates the final position of the deposited conductive fluid 160which has been deposited by multiple drops. As is well known in the artof conductive fluid, the fluid typically hardens to form a solid, alsodenoted as 161. Hereafter, the shading of the figures does notdifferentiate between the fluid and the hardened fluid.

Referring to FIG. 6 a, there is illustrated one technique for removal ofexcess fluid 161 deposition by dropper means of a fluid using a flexibleblade 170.

Referring to FIG. 6 b, there is shown a cross-sectional view of the die90, channel 150, and deposited fluid 161 as in FIG. 5 a but in moredetail. In accordance with the present invention, the fluid 161 haswicked underneath a portion of the die 90 and has made physical contactwith the contact region 130 of the die 90. This embodiment illustratesthe case in which the connection to the die 90 is an electricalconnection. For example, as is well know in the thin film materials art,an electrical connection can be formed from a deposited fluid 161 a ifthe fluid contains a metallic precursor or is an electrically conductivepolymeric material. The material in the channel 150, after annealing, isin electrical contact with contact region 130 a. A connection so formedto the microsized device 90 enables the device to send and receive datain the form of digital or analog electrical signals. It is not necessarythat the conductive material physically contact the contact region 130 aas long as it is closely disposed, as is well know in the art ofdielectric current detection. The contact regions 130 a in FIG. 6 b mayinclude electrically responsive elements such as voltage or currentsources or voltage or current detectors, well known in the art of MSTdevices. The supportive structure 140 in FIG. 6 b aids wicking of thefluid 161 a to the contact region, since it ensures that there is spacebetween the top surface of the ablative film and the protective coating135, as well as between the top surface of the ablative film and thecontact region 130 a. The supportive structure 140 in FIG. 6 b alsohelps prevent wicking of the fluid 161 a to the contact region 130 a onthe right side of the die due to its contact with the top surface of theablative film.

Referring to FIGS. 7 a-7 c, there is shown a cross-sectional view of thedie 90, channel 150, and deposited fluid 160 as in FIG. 5 a but in moredetail for the case in which the connection to the die 90 is a photonicconnection. In this case, the material 160 deposited in the channel 150is optically transparent (designated by 161 b). In accordance with thepresent invention, the fluid 161 b has wicked underneath a portion ofthe die 90 and has made physical contact with the contact region 130 bof the die 90. In the case that the fluid 161 b is an opticallytransparent material, for example a polymer such as polycarbonate orbenzo chlorohexal borene, the material 161 b in the channel 150, afterhardening or annealing, is in optical contact with the contact region130 b on the die. In this case, the contact region 130 b comprisesoptically responsive elements, for example LED optical sources made fromorganic polymers, or photodetectors, made, for example, form depositedfilms such as ZnSe or doped silicon semiconductor junctions. Aconnection so formed to the microsized device 90 enables the device tosend and receive data in the form of digital or analog optical signals.It is not necessary that the optically transmissive material physicallycontact the contact region 130 b as long as it is closely disposed sincelight can travel across the gap between the transmissive material andthe optical sensor. The supportive structure 140 in FIG. 7 c aidswicking of the fluid 161 b to the contact region on the left of the die,since it ensures that there is space between the top surface of theablative film and the contact region 130 b. The supportive structure 140in FIG. 7 c additionally prevents wicking of the fluid to the contactregion 130 b on the right side of the die due to its contact with thetop surface of the ablative film.

It is noted that electrical contacts 130 a may be disposed on the leftportion of the die 90 and are connected as disclosed above.

Referring to FIGS. 8 a-8 c, there is shown a cross-sectional view of adie 90, channel 150, and deposited fluid 161 c as in FIG. 5 a but inmore detail for the case in which the connection to the die 90 is amagnetic connection. In this case, the material 161 c deposited in thechannel 150 is a magnetically active material having a high magneticpermittivity (designated as 161 c). In accordance with the presentinvention, the fluid 161 c has wicked underneath a portion of the die 90and has made physical contact with the contact regions 130 c of the die90, which regions are shown as a pair of channels which serve to conducta magnetic field to and from a contact region 130 c which is sensitiveto an applied field, for example, contact region 130 c could be a Halltype magnetic field sensor. In the case that the fluid 161 c is amagnetically active material, for example iron or iron alloys, thematerial in the channel 150, after hardening or annealing, is inmagnetic communication with the contact regions 130 c on the die 90. Inthis case, the contact regions 130 c comprise a magnetically responsivecircuit, for example a Hall sensor, or, a source of magnetic fields, forexample, a moveable mechanical transducer having a magnetic portion, asis well known in the art of MST devices. A connection so formed to themicrosized device 90 enables the device to send and receive data in theform of digital or analog magnetic signals. It is not necessary that themagnetically active material physically contact the contact regions 130c as long as it is closely disposed to the contact regions 130 c, sincea magnetic field can be sensed across a gap between the material and thefield sensor.

Referring to FIGS. 9 a-9 c, there is shown a cross-sectional view of amicrosized device or die 90, channel 150, and an overlying conformallaminate film 180 for the case in which the connection to the die 90 isa fluidic connection. It is noted in the figures that color does notdifferentiate a channel 150 which is empty and a channel which is filledwith externally sampled fluid 161 d. In this case, the contact region130 d includes means responsive to the chemistry or rheology of thefluid 161 d present in the channel 150, for example the contact region130 d may be a chemically sensitive field effect transistor (CHEM-FET)sensitive (which is designated as 130 d), for example, to the ioniccontent of the externally sampled fluid 160 d (for example a gas orliquid); or the contact region 130 d may be a conductivity detector, ahumidity detector, a gas sensor, or a molecularly specific sensor suchas a MIP resonator. The contact region 130 d may also be a fluidicopening built into the microdevice itself, to convey fluids to thedevice for biological analysis or processing. In this case, themicrodevice may include pump means for drawing or dispensing theexternally sampled fluid 161 d in the channels 150. Externally sampledfluids 160 d may include either liquids or gases. In one embodiment ofthis case, there is no material deposited in the channel 150 but aconformal laminate film 180 (FIG. 9 c) has been placed at least overthose portions of the die 90 where channels 150 have been formed toserve as a cap to the channel.

It is noted the left portion of the die 90 may include electricalcontacts 130 a which are connected as described above.

Alternatively (FIGS. 10 a-10 f), a sacrificial material may be placed inthe channels 150, for example a phase change liquid such as a wax may bedeposited in the channels and hardened by cooling. In accordance withthis embodiment, the sacrificial fluid 161 e may wick underneath aportion of the die 90 and make physical contact with the contact region130 d of the die 90. A fluid sealant may then be coated, for example bydip or spray coating over the entire ablative film or at least theportion having die and channels, and the sacrificial material 161 esubsequently removed to form channels 150 for the externally sampledfluid 161 d. The sacrificial material 161 e may be removed (indicated by161 d), for example, by chemical dissolution or by heating to vaporizethe material. In accordance with either procedure, a fluid channel 150is formed in the ablative film in fluid communication with the contactregion(s) of the die 90. A connection so formed to the microsized deviceenables the device 90 to respond to chemical content, for example thepresence of salt in a fluid already present in the channel, or to fluidintroduced and/or removed from the channel, as sensed, for example, bythe pressure or the dielectric constant of the fluid. Similarly if thefluid is a gas, the sensor may detect molecular species such as ethanethat diffuse or circulate in the channels.

Referring to FIGS. 10 a-10 f, there is shown a cross-sectional view of adie 90, channel 150, and deposited overlayer for another exemplary casein which the connection to the die 90 is a fluidic connection. In thiscase, the contact region 130 is a fluidic opening built into the end ofthe microdevice itself, rather than an opening or a sensor defined onthe surface of the device, to convey fluids to the device for biologicalanalysis or processing. The microdevice may include pump means fordrawing or dispensing fluid in the channels 150 and data analysis meansto analyze chemical or biological properties of fluids in themicrodevice, such fluid functions being well known in the field of micrototal analysis system. In FIGS. 10 a-10 c, provision is also included onthe right of the microdevice for channel connections that are electricalin nature, as discussed in association with FIG. 6 a-6 c. In fact, thepresent invention envisions the use of multiple types of connections tosingle die and between die 90, including connections of the electrical,photonic, magnetic, and fluidic types. In FIG. 10 a-10 c, the fluidicchannels are formed using the process of fluid deposition of asacrificial material followed by coating of a sealing layer and thenremoval of the sacrificial material, as discussed above.

Referring to FIGS. 11 a-11 c, there is shown a cross-sectional view of adie 90, channel 150, and channel material 161 f for another exemplarycase in which the connection to the die 90 is a mechanical connection.In this case, the contact region 130 f is mechanically responsive andtherefore capable of sensing or producing static motion of the channelmaterial (strain) or sensing or producing oscillatory motion, i.e.acoustic waves. Many microdevices are known in the art of MSTtechnology, such as piezo cantilevers and electrostatic actuators, thatare capable of all such functions. In FIG. 11 a-11 c, provision is alsoincluded on the right of the microdevice for channel connections thatare electrical in nature, as discussed in association with FIG. 6 a-6 c.The present invention envisions the use of multiple types of connectionsto and between multiple types of die, including connections of theelectrical, photonic, magnetic, mechanical, and fluidic types.

Referring to FIGS. 12 a-12 b, there is shown a top and cross-sectionalview of a die 90, channel 150, and channel material 160 for the case inwhich the connection to the die 90 is remote, that is the material inthe channel 150 is close to the contact region 130 of the die 90 but notin physical contact. As shown in FIG. 12 b, which contemplates the caseof a fluid 160 deposited in the channel 150, no wicking of the fluid 160has occurred under the die 90. This may be accomplished by choosing thesurface of the die 90 and the fluid 160 so that the interfacial surfacetension is low and does not favor wicking, for example aqueous basedfluids will not generally wick under a die that is Teflon coated. Inthis case, the contact region 130 is still capable of sensing orreceiving or sending electrical, photonic, magnetic, mechanical, andfluidic connections but at a reduced sensitivity. Many microdevices areknow in the art of MST, such as magnetic detectors and temperaturesensors that can detect small changes in fields, produced by say acurrent flow depicted on the right side of FIG. 12 a, or by smallchanges in temperature, produced, say, by the flow of a warm fluid asdepicted on the left side of FIG. 12 a.

Finally, referring to FIG. 13, there is illustrated a top view of anablative film 70 having multiple microsized devices with multipleconnections of multiple types, including connections of the electrical,photonic, magnetic, mechanical, and fluidic types. Such arrays ofinterconnected microsized devices, including devices that generate andrespond to electrical, photonic, magnetic, mechanical, and fluidicsignals, function as microsystems, as is well known in the MST art. Ashas been discussed, and as shown in FIG. 13, the present inventioncontemplates that the connections are made to devices that are notprecisely positioned on the ablative film. Channels 150 can be formed ina self aligned manner by focused radiation (e.g. lasers) by detecting,for example with a digital camera, the positions of the microsizeddevices, storing this information in a memory file, and using theinformation from such files to scan the focused radiation beams towardthe desired locations on the die. (typically the locations of thecontact pads).

The invention has been described with reference to a preferredembodiment. However, it will be appreciated that variations andmodifications can be effected by a person of ordinary skill in the artwithout departing from the scope of the invention.

PARTS LIST

-   5 ablative film-   10 substrate-   20 energy-absorbing layer-   30 multiple layers-   40 channel-   50 base-   60 conductor-   70 ablative film-   75 energy-absorbing layer-   80 substrate-   90 die-   100 channel-   110 metallic bond pads-   120 liquid-   130 contact regions-   130 a conductive contacts-   130 b optical contacts-   130 c magnetic contacts-   130 d external contacts-   130 f mechanical contact-   135 protective layers-   140 raised support structure-   150 channels-   160 fluid-   160 a conductive ink-   160 d externally sampled fluid-   161 hardened liquid (solid)-   161 a conductive material/deposited fluid-   161 b optical connection-   161 c magnetic connection-   161 d external connection-   161 e sacrificial connection-   161 f mechanical connection-   170 flexible blade-   180 conformal laminate film

1. An apparatus comprising: (a) an ablative base material having atleast a top surface; (b) a die with at least a first surface of the diecontacting at least a first surface of the ablative base material; and(c) a channel disposed in the ablative material proximate to, but notfacing the die.
 2. The apparatus in claim 1 further comprising aconductive and wickable fluid in the ablated channel to provide contactto portions of the die by the wicking of the fluid.
 3. The apparatus ofclaim 1, wherein the channel is aligned the pre-positioned microdevice.4. The apparatus of claim 1, wherein the conductive material is a fluid.5. The apparatus of claim 1, wherein the conductive material is anelectrical conductor.
 6. The apparatus of claim 1, wherein theconductive material is a magnetic material.
 7. The apparatus of claim 1,wherein the conductive material conveys light.
 8. The apparatus of claim1, wherein the conductive material is responsive to sound or motion. 9.The apparatus of claim 1 further comprising structures on the microsizeddevices to facilitate fluidic, electrical, photonic, and mechanicalconnections to the devices.